Pop culture

• M31, a Psychedelic Punk band, based out of Los Angeles, California
  Los Angeles, California
  Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...
  
  
• M31: A Family Romance, a novel by writer Stephen Wright
  Stephen Wright (writer)
  Stephen Wright is a novelist based in New York City known for his use of surrealistic imagery and dark comedy. His work has varied from hallucinatory accounts of war , a family drama among UFO cultists , carnivalesque novel on a serial killer, to a picaresque taking place during the Civil War...
  
  

Highways

• M31 motorway
  M31 motorway
  The M31 motorway was planned as a Reading to M3 motorway which was dubbed the 'M3 – M4 link motorway'. It would have provided a direct high speed route between the two motorways...
  
  , a planned but unbuilt motorway in England
• M-31 (Michigan highway)
  M-31 (Michigan highway)
  M-31 was a state trunkline highway in the Lower Peninsula in the US state of Michigan. It served as a connecting route between Saginaw, The Thumb communities, and Port Huron.-Route description:...
  
  , a former state highway in Michigan
• Hume Highway
  Hume Highway
  The Hume Highway/Hume Freeway is one of Australia's major inter-city highways, running for 880 km between Sydney and Melbourne. It is part of the Auslink National Network and is a vital link for road freight to transport goods to and from the two cities as well as serving Albury-Wodonga and...
  
   in Australia, designated "M31" in the state of Victoria
• M31 motorway (Hungary)
  M31 motorway (Hungary)
  The M31 motorway is a motorway in Hungary. The motorway is between M0 at Nagytarcsa and M3 at Gödöllő and has been completed in July 2010.-External links:*...
  
  , a short motorway section near Budapest, Hungary

Military

• Suomi M-31 SMG
  Suomi M-31 SMG
  The Suomi KP/-31 was a submachine gun of Finnish design that was in service during World War II. It was a descendant of the M-22 prototype and the KP/-26 production model, which was revealed to the public in 1925...
  
  , a Finnish WWII-era submachinegun
• M31 HEAT rifle grenade
  M31 HEAT rifle grenade
  The M31 HEAT is a fin-stabilized anti-tank rifle grenade designed in the late 1950s to replace the Belgian ENERGA rifle grenade which was adopted by the US Army and US Marines as an emergency stop-gap measure during the Korean War...
  
  
• M31 Recovery Vehicle based on the M3 Lee
  M3 Lee
  The Medium Tank M3 was an American tank used during World War II. In Britain the tank was called "General Lee", named after Confederate General Robert E. Lee, and the modified version built with a new turret was called the "General Grant", named after U.S. General Ulysses S. Grant.Design commenced...
  
   tank
• M31 rocket, an alternate designation for the MGR-1 Honest John
  MGR-1 Honest John
  The MGR-1 Honest John rocket was the first nuclear-capable surface-to-surface rocket in the US arsenal.The first nuclear-authorized guided missile was the MGM-5 Corporal. Designated Artillery Rocket XM31, the first such rocket was tested 29 June 1951 and the first production rounds were delivered...
  
  , a United States military rocket
• M31 missile, MLRS
• M31 is the pennant number for HMS Cattistock
  HMS Cattistock (M31)
  HMS Cattistock , the third ship of this name, is a Hunt-class minesweeper of the Royal Navy. She was launched in 1981 and commissioned on 5 March 1982, the third ship of her class....
  
  , a Hunt-class mine countermeasures vessel